Not Applicable.
This invention relates to scroll compressors, expanders, and vacuum pumps where grease, dampening gel or epoxy is used for improving the performance of the device.
Scroll devices have been used as compressors and vacuum pumps for many years. In general, they have been limited to a single stage due to the complexity of two or more stages. Oil free or oilless scroll type compressor and vacuum pumps are difficult and expensive to make, due to the high precision needed for the scrolls. For oil lubricated scroll compressors and vacuum pumps, swing links are often used to minimize the leakage gaps in the scrolls by allowing the scrolls to contact on the scroll surfaces. Swing links cannot be used in an oil free or oilless scroll compressor due the to friction and wear that will occur in the absence of lubrication. If the scrolls are not precisely made in an oil free scroll compressor, then leakage can occur, and performance will drop.
In U.S. Pat. No. 4,802,837 to Kazutaka, a scroll compressor is disclosed in which the scroll is coated with a plastic material by injection molding. Although this method reduces the cost of machining the scrolls, it still requires injection molding, and, if the unit is oilless, machining will be needed on the plastic to achieve good performance. The injection molding of scrolls is thus expensive.
In U.S. Pat. No. 5,803,723, also to Kazutaka, another scroll compressor is shown in which a coating is applied to the scroll. The coating is then worn off using a swing link with a fixed stop. As noted above, the use of a swing link is expensive. The patent does not teach how the coating is applied, however, the coating is thicker than needed so that some of the coating can be worn off.
Briefly stated, a scroll compressor having improved efficiencies includes a fixed plate having a spiral involute and an orbiting plate having a spiral involute wrap. The fixed and orbiting plates are positioned in a housing such that the spiral involute wraps mesh with each other to define chambers. A tip seal and sealant is applied to tips and sides of the involute wraps, the tip seal and sealant substantially close any leakage gaps between the tip of the involute wrap and the plate opposing the involute wrap and the sides of the involute wraps. The sealant is chosen from the group consisting essentially of a grease, a dampening gel, and a one or two part epoxy. If a grease is used, then the grease is preferably a low vapor pressure grease.
During assembly of the scroll compressor, the sealant is applied to the tips and sides of the involute wraps. After the scroll compressor has been assembled, it is run to purge excess sealant, leaving sealant only in the gaps between the two scrolls. If an epoxy is used as a sealant, and the epoxy requires curing, the scroll compressor is disassembled after the initial run and the epoxy is cured. The scroll compressor is then reassembled.